1. Field of the Invention
The present invention relates generally to wrenches and, more particularly, to an adjustable wrench having a sliding side jaw.
2. Description of the Prior Art
An powered adjustable wrench having a moveable jaw and a stationary jaw is known in the prior art. As illustrated in FIG. 1A, the powered adjustable wrench 1 of the prior art includes a wrench body having a wrench head 2 formed integrally with the stationary jaw 3 and the moveable jaw 4 adjustable relative to the stationary jaw 3. A worm gear 5 having a pulley 6 is rotated by a belt 7 and a motor pulley 8. The moveable jaw 4 is provided with an integral gear rack for engagement with the worm gear 5. The worm gear 5 is positioned between the fixed jaw 2 and the pulley 6. A double pole double throw (DPDT) switch 9 is used to control the opening and closing of the moveable jaw 4. With an upper handle housing removed, a bottom handle housing 10 houses an electric motor 12 connected to the motor pulley 8 by a shaft 13. Wires 14 and 15 connect the electric motor 12 with the DPDT switch 9 and batteries 16 supply power for the switch and motor. A sub mini jack 18 is used for recharging the batteries 16. The bottom handle housing 10 defines a battery recess 19 and a motor recess 20 containing the motor 12.
The moveable jaw 4 of the prior art, shown in FIG. 2, has a gear rack portion 4a including a toothed segment 4b. As illustrated in FIG. 2, a lead of a first tooth starts immediately at one distal end 4c of the gear rack portion 4a. Another distal end 4d of the gear rack portion 4a is not toothed. Such arrangement stops the worm gear 5 from movement in the direction away from the stationary jaw 3 and prevent the moveable jaw 4 from exiting out an open end of the wrench head 2. This, only one end of the gear rack portion 4a of the moveable jaw 4 is non-toothed to stop the outward movement of the moveable jaw 4.
The worm gear 5 of the prior art, shown in FIG. 3, includes a continuous screw thread 5a drivingly engaging teeth of the toothed segment 4b of the gear rack portion 4a of the movable jaw 4. Conventionally, the screw thread 5a has opposite start lead 5b and exit lead 5c that run out to opposite ends of the worm gear and gradually taper off.
As illustrated in FIG. 1B, the stationary jaw 3 has a jaw surface 3′, while the movable jaw 4 has a jaw surface 4′. Thus, as further shown in FIG. 1B, the adjustable wrench 1 of the prior art grips a conventional hexagonal bolt head and/or nut 11 on two opposite sides thereof.
However, the powered adjustable wrenches of the prior art suffer certain drawbacks due to the fact that they rely on a motor torque to open and close its jaws 3, 4 and to stop the moveable jaw 4. In other words, the powered adjustable wrench 1 of the prior art relies on the motor 12 to stall in order to stop the moveable jaw 4. As was noted above, the prior art provides means for stopping the moveable jaw of the power wrench in only one direction, away from the stationary jaw (the full open position), in order to prevent the moveable jaw from exiting out the opened end of the wrench head. Wrenches of this type usually have rapid sliding jaw movement. However, a condition arises when the moveable jaw 4 is at full open position and then powered to the fully closed position. The rapid closing movement and inertia force of the moveable jaw 4 hammers and collides with the stationary jaw 3 to an abrupt stop, which creates the condition that locks-up the power wrench 1 between the moveable jaw 4 and the stationary jaw 3. The powered adjustable wrenches of the prior art do not have means to control positioning and stopping of the moveable jaw at predetermined stops for both open and close directions.
Furthermore, the adjustable wrench of the prior art grips the conventional hexagonal bolt head only on two opposite sides thereof.